This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPPthird generation partnership projectACKacknowledge (positive acknowledge)ARQautomatic repeat requestBTSbase transceiver systemC-RNTI cell-radio network temporary identifierCSIchannel state informationDLdownlink (eNB, Node B towards UE)eNBEUTRAN Node B (evolved Node B, or eNodeB)EUTRANevolved UTRAN (LTE)GGSNgateway general packet radio system support nodeLTElong term evolutionMACmedium access controlMIMOmultiple input, multiple outputMM/MMEmobility management/mobility management entityMU-MIMOmulti-user MIMONACKnot acknowledge/negative acknowledgeNBAPNode B application part (signaling)Node B base station (includes BTS)OFDMAorthogonal frequency division multiple accessO&Moperations and maintenancePCFICHphysical control format indicator channelPDCCHphysical downlink control channelPDSCHphysical downlink shared channelPHICHphysical hybrid ARQ indicator channelPRBphysical resource blockP-RNTIpaging-radio network temporary identifierPUCCHphysical uplink control channelPUSCHphysical uplink shared channelRACHrandom access channelRANradio access networkRA-RNTI random access-radio network temporary identifierRBresource blockREresource elementREGresource element groupRFradio frequencyRLCradio link controlRNCradio network controllerRRCradio resource controlSC-FDMA single carrier, frequency division multiple accessSI-RNTI system information-radio network temporary identifierSPS-RNTIsemi-persistent scheduling-radio network temporaryidentifierSSsearch spaceTCPtransmission control protocolUEuser equipmentULuplink (UE towards eNB, Node B)UTRANuniversal terrestrial radio access network
One modern communication system is known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA). In this system the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.11.0 (2009 December), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.3.0 (2010 March).
FIG. 1 reproduces Figure 4.1 of 3GPP TS 36.300 V8.11.0, and shows the overall architecture of the EUTRAN system (Rel-8). The E-UTRAN system includes eNBs, providing the E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UEs. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to a S-GW by means of a S1 interface (MME/S-GW 4). The S1 interface supports a many-to-many relationship between MMEs/S-GWs/UPEs and eNBs.
The eNB hosts the following functions:
functions for RRM: RRC, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both UL and DL (scheduling);
IP header compression and encryption of the user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards the EPC (MME/S-GW);
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
a measurement and measurement reporting configuration for mobility and scheduling.
Of particular interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10) targeted towards future IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference in this regard may be made to 3GPP TR 36.913 V9.0.0 (2009 December) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for further advancements for Evolved Universal Terrestrial Radio Access (E-UTRA) (LTE-Advanced) (Release 9). Reference can also be made to 3GPP TR 36.912 V9.3.0 (2010-06) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Feasibility study for Further Advancements for E-UTRA (LTE-Advanced) (Release 9).
A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. While LTE-A has provided many such services, the services could still be improved.